flake: overlays: convert to 'flake-parts'

flake/default.nix

@@ -73,13 +73,15 @@ let
   systemIndependant = {
     lib = import ./lib.nix inputs;
 
-    overlays = import ./overlays.nix inputs;
-
     nixosConfigurations = import ./nixos.nix inputs;
   };
 in
 flake-parts.lib.mkFlake { inherit inputs; } {
   systems = mySystems;
 
+  imports = [
+    ./overlays.nix
+  ];
+
   flake = (eachMySystem systemDependant) // systemIndependant;
 }

flake/overlays.nix

@@ -1,5 +1,4 @@
 { self, ... }:
-
 let
   default-overlays = import "${self}/overlays";
 
@@ -13,4 +12,6 @@ let
     };
   };
 in
-default-overlays // additional-overlays
+{
+  flake.overlays = default-overlays // additional-overlays;
+}